yearling vs nestling

yearling and nestling both are nouns.

Word	Noun	Adjective	Verb	Adverb
yearling	Yes	No	No	No
nestling	Yes	No	No	No

As nouns, nestling is a hypernym of yearling; that is, nestling is a word with a broader meaning than yearling:

Other hypernyms of yearling include child, fry, kid, minor, nipper, shaver, small fry, tiddler, tike, tyke, youngster.

yearling (noun)	nestling (noun)
an animal in its second year	young bird not yet fledged
a racehorse considered one year old until the second Jan. 1 following its birth	a young person of either sex
a young child who is just beginning to walk